As the display technology develops and evolves, current display technology pursues to provide a three-dimensional (3D) stereo display with an optimal immersive effect. Most stereo image display technologies implement a concept that an image signal is divided into left-eye images and right-eye images having different visual angles. The left-eye images and the right-eye images are respectively transmitted to the left eye and the right eye of a viewer via a stereo image display, and are then projected into a stereo image in the human brain. Accordingly, the left-eye images and the right-eye images are interleaved with each other in a common stereo image signal. However, a sequence of the left-eye images and the right-eye images is not particularly designated in the common stereo image signal, i.e., positions of the left-eye images and the right-eye images are not designated. Therefore, in order to accurately transmit the left-eye images and right-eye images to the left eye and the right eye, respectively, it is crucial to first detect the sequence of the left-eye image and right-eye image of the stereo image.